To create a manual load combination

To manually create an individual combination of existing load cases, use the following procedure.

On the Model ribbon tab, select the Load Combination tool in the Loads group.

The Add Load Combination dialog opens.
Type a unique Name and (optional) Description for this load combination.
Select the Type of combination method to use.
- Linear – A pure algebraic load combination in which the results of all constituent cases will be algebraically added.
  Ex.: $f_{1} \times L_{1} + f_{2} \times L_{2} + f_{3} \times L_{3}$
- SRSS – The square root of the sum of the squares method of combination.
  Ex. $f_{1} \times L_{1} + f_{S R S S} \times \sqrt{f_{2} L_{2}^{2} + f_{3} L_{3}^{2}}$
- ABS – Algebraic combination of absolute values.
  Ex.: $f_{1} \times | L_{1} | + f_{2} \times | L_{2} | + f_{3} \times | L_{3} |$
(Optional) Select an Analysis set with which you want to associate this load combination.
Note: This option is only available when the REPEAT Primary Load Cases option for Combination Load Cases is selected in the Options dialog Analysis model tab.
For SRSS combinations, type an SRSS Factor.
(Optional) Check the option to Include load groups to add these to load cases. A Load group factors control is added.
To filter the types of load (i.e., dead, live, etc.) included in the load combination:
1. Click in the Load case filter field.
2. Check the box for each load type to include.
To specify the load factors used for each load case:
1. Click in the Factors field.
2. Type the load Factor to use as a multiplier for the load case.
3. (Optional) Check the SRSS option for any load cases to be added by the SRSS method in a SRSS load combination. Load cases that do not have this option checked will be added algebraically in an SRSS combination.
If you have selected to include load groups, then repeat step 7 for load group factors.
Click OK.

You can view and edit load combinations by selecting the Load combinations tool in the Reference group on the Spreadsheet ribbon tab.

Select a load combination in the spreadsheet to preview the combined load in the view window.

Note: Both algebraic and SRSS combinations will display as factor × load, with the initial sign of the load preserved (SRSS factors are not utilized when displaying those loads). For ABS loads, the absolute value of the factor × |load| is used for the display.